The xerographic imaging process begins by charging a photoconductive member to a uniform potential, and then exposing a light image of an original document onto the surface of the photoreceptor, either directly or via a digital image driven laser. Exposing the charged photoreceptor to light selectively discharges areas of the surface while allowing other areas to remain unchanged, thereby creating an electrostatic latent image of the document on the surface of the photoconductive member. A developer material is then brought into contact with the surface of the photoreceptor to transform the latent image into a visible reproduction. The developer typically includes toner particles with an electrical polarity opposite that of the photoconductive member. A blank copy sheet is brought into contact with the photoreceptor and the toner particles are transferred thereto by electrostatic charging the sheet. The sheet is subsequently heated, thereby permanently affixing the reproduced image to the sheet. This results in a "hard copy" reproduction of the document or image. The photoconductive member is then cleaned to remove any charge and/or residual developing material from its surface to prepare it for subsequent imaging cycles.
Electrostatographic imaging members are well known in the art. One type of photoreceptor conventionally utilized for copiers and printers comprises a hollow electrically conductive drum substrate which has been dip coated with various coatings including at least one photoconductive coating comprising pigment particles dispersed in a film-forming binder. These photoreceptors are usually supported on an electrically conductive shaft by drum supporting hubs or end flanges. The hubs are usually constructed of plastic material and have a hole through their center into which a supporting axle shaft is inserted. Since hubs are usually constructed of electrically insulating plastic material, an electrical grounding means comprising a flexible spring metal strip is secured to the hub and positioned to contact both the electrically conductive axle shaft and the electrically conductive metal substrate of the photoreceptor drum. One type of grounding means is illustrated in U.S. Pat. No. 4,561,763 to Basch issued Dec. 31, 1985, the contents of which are hereby incorporated by reference. A drum supporting hub is disclosed having a tapered pot-like hub configuration comprising a bottom section and a rim, the rim comprising a plurality of circumferentially spaced resilient fingers extending at a slight incline outwardly from the axis of the pot-like hub away from the bottom section, at least three of the fingers having lips at the ends of the fingers, the lips projecting away from the axis for engagement with an end of a cylindrical drum upon insertion of the pot-like hub into the drum, the rim other than the lips having an outside diameter slightly larger than the outside diameter of the bottom. The drum supporting hub is employed in a drum assembly comprising the hub, a cylindrical drum having a circular cross-section and a shaft positioned along the axis of the drum. In one embodiment the hub is plastic, which is made of or coated with an electrically conductive material to permit electrical grounding of the drum through a shaft passing through the hub. In another embodiment, a metal shim is utilized to electrically ground the drum to the shaft.
Unfortunately, this metal ground shim is often bent out of alignment when inserted into one end of a photoreceptor drum. Such misalignment can result in the metal strip not contacting the interior of the drum or the axle or both after insertion of the hub into the end of the drum is completed. Further, coatings electrically insulating in the dark that are formed on the surface of the interior of the drum during dip coating can adversely affect electrical grounding of the drum to the electrically conductive drum axle shaft. If inadequate electrical grounding of the drum to the axle shaft is detected after the drum has been inserted into a modular replacement unit in which photoreceptor and various other subsystems such as cleaning and charging units are permanently mounted, repair of the drum is usually impossible without destruction of the module.
Photoreceptors presently available in the art are often secured to the hub or end flange with a thermosetting resin adhesive. An example of this type of device is disclosed in U.S. Pat. No. 4,914,478 to Yashiki issued Apr. 3, 1990, the contents of which are hereby incorporated by reference. However, recycling of used drums having glued hubs is difficult, if not impossible, because of damage to the hub or the drum or both during removal of the hub from the drum by common techniques such as by hammering. Such removal techniques damage or destroy both the drum and the hub. Further, where disassembly is accomplished without damage, cleaning of both the hub and the cylindrical substrate is required to remove adhering adhesive. In addition, adhesive application equipment utilized during mounting of an end flange to a cylindrical substrate are difficult to maintain because the adhesive has a short pot life and often solidifies and clogs the equipment thereby requiring time consuming efforts to clean and remove the solidified adhesive. The use of bolts and nuts to secure hubs to drums requires time intensive activity and does not address the problem of electrically grounding a drum substrate to the drum axle shaft.
One existing end flange device which avoids the use of adhesive materials is U.S. Pat. No. 5,357,321 to Stenzel et al. issued Oct. 18, 1994, which utilizes resilient fingers having pointed tips that dig into and penetrate the inner surface of the drum. A drum supporting hub is disclosed comprising a disk shaped member having a circular periphery, a hole extending axially through the center of the disk shaped member, and at least one long thin electrically conductive resilient member secured to the disk shaped member, the resilient member having a central section adjacent the hole and having opposite ends, each of the ends terminating into at least one pointed tip adjacent the circular periphery of the disk shaped member, and the resilient member having a major plane substantially parallel to the axis of the disk shaped member. This hub may be inserted in at least one end of a cylindrical electrostatographic imaging member to produce an imaging member assembly. While this hub may adequately support the photoreceptor, the pointed tips can for m scratches and grooves in the interior surface of the drum during installation, use and removal. These scratches or grooves can adversely affect recycling of the cylindrical substrate.
Another glueless arrangement is disclosed in U.S. Pat. No. 5,461,464 to Swain issued Oct. 24, 1995, which discloses a photoreceptor assembly including a substrate coated with a photoconductive material, and with flange members engaged with the end sections of the substrate. The flange member engaged with the first end section is comprised of a projection which fits into the surface hole of the first end section. The flange member at the second end includes a projection which fits into a surface hole that resides in the second end section. There is no adhesive present between the engaging surfaces of the substrate and the flange members.
U.S. Pat. No. 5,630,196 to Swain issued May 13, 1997, discloses a hollow cylinder supporting end flange including a disk shaped member having a circular periphery and a coil spring having a major plane substantially parallel to the major plane of the disk shaped member. The coil spring also has an exposed arcuate outer periphery with a diameter larger than the inside diameter of the hollow cylinder, an outer exposed end and an inner end, with the inner end comprising a section secured to the end flange and the exposed arcuate outer periphery of the coil spring being adjacent the circular periphery of the disk shaped member for engagement with a hollow cylindrical member upon insertion of the coil spring into the hollow cylindrical member. The end flange may be utilized as a component of an assembly including a hollow cylindrical electrostatographic imaging member having a circular cross section and an inner surface, and an end flange secured to at least one end of the hollow cylindrical member by a partially wound coil spring, the spring having an inner end and an outer end, the inner end being secured to the end flange and the outer end having an exposed arcuate outer surface in frictional contact with the inner surface of the hollow cylindrical member. A process for fabricating this assembly is also disclosed.
U.S. Pat. No. 5,599,265 to Foltz issued Feb. 4, 1997 discloses a hollow cylinder supporting end flange comprising a disk shaped member, a supporting hub extending axially from the disk shaped member and an annular ring supported on the hub, the ring comprising a plurality of sharp protrusions or barbs extending from the ring in a direction away from the hub for engagement with the hollow cylindrical member upon insertion of the annular ring into the hollow cylindrical member. This end flange is utilized in an assembly comprising a hollow cylindrical member having a circular cross section and an inner surface and an end flange comprising a disk shaped member having a circular periphery, a supporting hub extending axially from the disk shaped member into one end of the hollow cylindrical member and an annular ring supported on and secured to the hub, the ring comprising a plurality of sharp protrusions extending from the ring in a direction away from the hub into engagement with inner surface of the hollow cylindrical member to secure the hollow cylindrical member to the end flange.
U.S. Pat. No. 4,400,077 to Kozuka et al. issued August 1983 discloses a photosensitive drum assembly for an electrostatic copying apparatus which includes a cylindrical drum with a photosensitive layer around its outer periphery. The drum is held between a pair of flanges at opposite axial ends of the drum. Each of the flanges is formed having a diameter larger than the external diameter of the drum. At the edge of each flange is a cylindrical portion extending along the axis of the drum to face toward the opposite flange. The end edges of the drum closely fit into the cylindrical portions.
U.S. Pat. No. 4,120,576 to Babish issued Oct. 17, 1978 discloses a drum support apparatus including outboard and inboard hubs having outer surfaces and adapted for interface fitting with the inside surface of the drum. The hubs are supported on a shaft that is cantilevered from a frame and have recessed areas on central portions to cooperate with locking tabs located on a tubular member loosely fitted on the shaft.
U.S. Pat. No. 5,402,207 to Michlin issued Mar. 28, 1995 teaches a conductive photoreceptor drum gear that may be made of metal. When the bushing for the gear is smooth metal, a conductive joining material is used to fix the bushing with respect to the photoreceptor, insuring electrical contact between the bushing and the photoreceptor. When the bushing for the gear has prongs, the prongs dig into the inner wall of the photoreceptor and establish electrical contact with the photoreceptor. When the bushing for the gear is knurled, the knurls cut into the inner wall of the photoreceptor to establish electrical contact with the photoreceptor and a non-conductive joining material can be used to insure that the gear is fixed with respect to the photoreceptor.
U.S. Pat. No. 5,634,175 to Michlin et al. issued May 27, 1997 teaches an electrical contact device for a developer roller in a toner cartridge. A developer roll contact device having a smooth flange which fits snugly inside the end of the developer roll and is used to establish electrical contact between the developer roller and the printer electrical contact. Developer roller contact device may be made of conductive plastic and may be fitted to the developer roller without adhesive.
U.S. Pat. No. 5,815,773 to Zaman issued Sep. 29, 1998 discloses a composite photoreceptor flange with an end flange made from a composition which includes polycarbonate, polytetrafluoroethylene, and glass. The mounting of the end flange in the photoreceptor does not require the use of an adhesive material. A grounding plate is necessary in order to provide an electrical ground for the photoreceptor.
U.S. Pat. No. 4,100,480 to Lytle et al. issued Jul. 11, 1978 teaches a position and velocity sensor. A linear voltage differential transformer is used to control the positioning of an element at either of two positions.
U.S. Pat. No. 5,893,203 to Buttrick, Jr. issued Apr. 13, 1999 discloses a process for seating a tight-fitting headed fastener in a hole in a workpiece so that the head of the fastener contacts the workpiece. A fastener is inserted into a hole in the workpiece and a driver contacts the head of the fastener and senses and records the position of the fastener head to determine how far the fastener must be driven into the hole to seat the fastener head against the workpiece surface.
All of the references cited herein are incorporated by reference for their teachings.
Accordingly, although known apparatus and processes are suitable for their intended purposes, a need remains for an apparatus which is capable of supporting hollow cylindrical support members without the use of an adhesive, to facilitate recycling.